1. Field of the Invention
This invention relates to the creation of amorphous materials, and more specifically, this invention relates to the processing of solids and liquids in the absence of nucleation points to create partially glassy or substantially glassy materials.
2. Background of the Invention
Amorphous compounds have enhanced solubility, faster dissolution rates and, in the case of drugs, higher bioavailability compared to their crystalline counterparts. This is due in part to the increased surface wetting of the disordered structure of amorphous materials and changes in the molecular shape or packing arrangements compared to crystalline materials.
Only a limited range of amorphous pharmaceutical compounds are commercially available. This is because synthesizing bulk amorphous forms of a drug is not always possible using conventional pharmaceutical processes, such as melt quenching in containers, freeze and spray drying, milling, wet granulation and the drying of solvated crystals. Also, attempts to make amorphous forms of low molecular weight drugs, such as aspirin (which has a molecular weight of 189 Daltons) have proven elusive.
State of the art methods for producing amorphous materials are inefficient, with a yield of less than 75 percent of the starting material being converted. Typically, about 40 percent yields are realized. Those methods are frequently relegated to small scale production of less than 500 milligrams.
Developing amorphous forms is becoming increasingly important due to the emergence of new drugs, many of which are virtually insoluble in their crystalline form.
A need exists in the art for a method for producing amorphous compounds at high conversion rates (i.e., above 75 percent). The method should be applicable to a wide range of target compounds. The method should also be applicable to convert compounds initially found in different non-glassy phases to amorphous phases which exhibit long shelf lives.